A rigorous bound on quark distributions in the nucleon

Abstract

I deduce an inequality between the helicity and the transversity distribution of a quark in a nucleon, at small energy scales. Then I establish, thanks to the positivity constraint, a rigorous bound on longitudinally polarized valence quark densities, which finds nontrivial applications to d-quarks. This, in turn, implies a bound for the distributions of the longitudinally polarized sea, which is probably not SU(3)-symmetric. Some model predictions and parametrizations of quark distributions are examined in the light of these results.

Talk given at the QCD03 Conference, Montpellier, 2-9 July 2003

References in corpus (2)

• Melosh rotation: source of the proton's missing spin
• Hermes and the spin of the proton